Field of Invention
The invention relates to a sealing arrangement for sealing a pressure chamber in a high pressure pump, as well as to a high pressure pump having such a sealing arrangement.
Background Information
The pressure chamber in a pump, in which a pressurized fluid to be conveyed by the pump is present, has to be sealed off with respect to its environment. In this connection the environment of the pressure chamber can be the environment of the pump typically present at atmospheric pressure, or—in the case of a multi-stage pump—a different pressure chamber of the pump in which the fluid to be conveyed is present at a higher or lower pressure.
The larger the pressure generated by the pump is the more difficult it is to provide efficient and reliable sealing arrangements. Having regard to high pressures of, for example, up to 1000 bar conveying pressure, pressure related elongations or deformations of the pump housing or of other components are frequently brought about. These can have the consequence that gaps open between components which bound the same pressure chamber, for example between the pump housing and the pump cover. Such gaps, which amongst other things can also arise due to different thermal expansions of the components, must then be reliably sealed in order to avoid a leakage of the fluid through the gaps.
The pressure induced opening of such gaps can, for example, be avoided or at least be limited to an uncritical degree, in that the components, between which the gap arises, are configured so stiff—and this generally means so thick-walled—that also for very high pressures only such small gaps arise such that the functionality of the sealing arrangement is not endangered. However, this has the disadvantage that significantly more material is required with regard to the thick-walled design and that the pump has a considerable increased weight. Both are rather disadvantageous effects from an economic point of view.
For this reason one strives to create sealing arrangements which also reliably and efficiently seal at very high pressures. Having regard to many sealing arrangements an O-ring is provided which is typically inserted into a groove of a sealing surface. In the International (PCT) patent application PCT/EP2012/071654, for example, a sealing arrangement is suggested having regard to which a groove-like recess is disposed in one of the components between which the seal should take place, the groove-like recess being configured in such a way that on an application of pressure of the groove a force is exerted in the direction onto the sealing surface of this component, which presses this sealing surface against the sealing surface of the component adjacent thereto. In this connection the application of pressure of the groove can bring about an elastic deformation or plastic deformation of its walls in order to thus avoid or to reduce the pressure induced opening of gaps between the components. An O-ring is provided in one of the two sealing surfaces contacting one another, the O-ring consisting of an elastomer and being arranged in a groove disposed in this sealing surface. This O-ring serves for a reliable seal between the two sealing surfaces contacting one another.
Specifically for sealing arrangements with O-rings the danger exists with regard to the extrusion of the O-ring. In this connection it is meant that the O-ring is deformed on the application of pressure in such a way that a part of it is pressed into a gap opening under pressure which can have the consequence of a damaging of the O-ring and in this way a loss of the sealing effect.